[ovirt-devel] [RFC] VM thread pinning for High Performance

Hey list, As a part of High Performance VMs feature [1], the oVirt virt team is planning to introduce a fine grained CPU pinning control for various VM threads (vcpu, io, emulator). Current idea for the pinning is to allow per-host configuration of the number of CPUs per numa node to be reserved for io+emulator threads. If we assume that the reservation will be done by 'reserved_cpus' variable, let's use this as an example: reserved_cpus = [0, 1] Such configuration would imply that 2 cores, 0th and 1st in each numa node may be used for io+emulator thread. Additional logic is required to avoid wasting these cores if single machine spans >1 numa node, roughly if numa_node where vcpu0 contains reserved_cpus: pin io/emulator thread to reserved_cpus else: reserve reserved_cpus in numa_node with vcpu0 pin io/emulator thread to reserved_cpus Such logic won't waste extra vcpus for large VMs. Any comments on the idea are more than welcome! [1] https://trello.com/c/MHRDD8ZO/67-high-performance-vm-preset-in-vm-dialog